The invention relates to an impervious cable connected electrical component assembly and the process of making such assembly.
Ocean data is frequently gathered by submerged sensors distributed along a cable. It is important that watertight integrity of each sensor be maintained so that signals from the sensor to the cable or vice versa are not shorted to the ocean water. A commonly used sensor is the hydrophone. Other sensors used are pressure transducers, accelerometers and/or thermistors. Recently the sensors have been combined with batteries, amplifiers and/or signal conditioning devices. Many of these sensors and devices are temperature and pressure sensitive. If the temperature or pressure gets too high during assembly these elements can be ruined or undergo calibration shifts.
By way of example, in an existing assembly, a cable that is hundreds of meters long has a multitude of distributed hydrophones attached to it. Each hydrophone is mounted as an appendage to the cable and is appropriately termed a "take out". Because these hydrophones are temperature and pressure sensitive great care must be taken in the process of attaching the hydrophones to the cable. Several construction methods are employed. After connecting the hydrophone to the cable, the connection and the hydrophone are encapsulated with a potting material, such as epoxy or polyurethane. These encapsulation materials are cured at room temperature and pressure. There are two serious problems with this process, namely: (1) long construction time and (2) insufficient watertight integrity of the hydrophone. The curing time of the encapsulation material can be as long as 24 hours for each hydrophone. It is not unusual to create an assembly in which dozens or more of hydrophones are attached to hundreds of meters or more of cable. The amount of labor and time to produce such an assembly can be readily appreciated. This can be aggravated when ventilation of the curing material is required for safety purposes. The other problem involving watertight integrity occurs because of a lack of sufficient bonding of the encapsulation material to the cable sheath. In the past the bonded materials were different, the cable sheath being Surlyn and the component encapsulation material being polyurethane. In the hydrophone application described above, once the bond breaks the hydrophone is rendered useless.